The present invention improves upon sterile disposable tubing sets used in hemodialysis. Sterile disposable tubing sets are advantageous in dialysis procedures because they need to be sterilized once and are only used once and are then discarded. In hemodialysis, the patient's blood is removed from the patient's body, anticoagulated, and circulated in an extracorporeal tubing circuit through a dialyzer or artificial kidney. This removes toxic substances such as urea and creatinine from the blood. Typically, a complete hemodialysis procedure is repeated every other day. Thus, because hemodialysis is performed so frequently, it is highly desirable to keep the cost of each treatment as low as possible. It is also very important to maintain sterility for patient safety. To achieve both of these ends, disposable blood tubing sets have been developed. Indeed, disposable sets such as those shown in Brugger, et al., U.S. Pat. No. 5,693,008 are preferred, because these tubing sets prevent contamination of the dialysis machine, which in turn prevents contamination of dialysis patients. This enhances safety and keeps the cost of each treatment down.
At the present time extracorporeal disposable dialysis tubing sets comprise one or more cannulae for drawing blood from and returning blood to a patient. The blood tubing set typically includes a plurality of medical tubing segments, bubble traps or drip chambers, pressure monitoring sites, air bubble detection sites, access sites, clamps, peristaltic pump headers and possibly numerous other sorts of accessories. As described further in Heath et al., U.S. Pat. No. 4,770,787, the extracorporeal tubing circuit can include a fluid flow cassette that can be mounted on a dialysis machine. The cassette would then preferably have one or more flexible tubes that extend from a sidewall to form a pump loop.
As mentioned, an extracorporeal blood tubing set includes a plurality of tubing segments, two of which particularly are the venous and arterial dialyzer tubing segments and their associated arterial and venous dialyzer connector ends. The venous dialyzer tubing segment comprises a venous dialyzer connector end which may be or may include a luer lock connector apparatus for connecting the venous dialyzer tubing segment to the dialyzer. The arterial dialyzer connector end is adapted to connect the arterial dialyzer tubing segment to the dialyzer as well. The arterial dialyzer connector end may also be or may include a luer lock type of connector. In conventional practice, both the venous and arterial connector ends are covered with loose-fitting caps preferably color-coded. The primary purpose of such caps is the maintenance of sterility of the tubing set and connector ends before installation onto the dialysis machine. A color-coding system has been used whereby the colors of these loose-fitting caps are matched with corresponding colors of the dialyzer ports to which they must be connected. The color coordination is meant to prevent confusion of the inlet and outlet ports on the dialyzer.
In use however, a disadvantage of loose-fitting caps occurs first when the caps are removed prior to connection to the dialyzer. Manually removing the caps covering the connectors provides a potential for contamination of the connector ends by the human operator of the dialysis machine. During this manual removal, the operator may inadvertantly touch the sterile connector end that connects to the dialyzer, rendering that connector end non-sterile.
Furthermore, in conventional practice, the distinct elements forming the connector ends have required that each connector end be manufactured separately. By manufacturing the connector ends as an integrally molded product, the cost of manufacturing the tubing set is decreased.
A breakable tubing coupling apparatus was disclosed in Folden, U.S. Pat. No. 5,221,267 for incorporation into a peritoneal dialysis conduit system. Specifically, the Folden patent describes using the breakable tubing coupling apparatus to remove tubing sections after fluid has passed therethrough. In the Folden apparatus, there is fluid communication through the tubing coupling apparatus before the breakable coupling apparatus is separated from the section of tubing entering the peritoneal cavity. The Folden breakable tubing coupling is used to detach tubing segments from the patient after peritoneal dialysis is completed.
It is toward the need to maintain a sterilizable tubing set, to simplify manufacturing and to prevent confusion in connecting the tubing set to both the dialysis machine and to the patient, that the present invention is directed.